Digital photography is a type of photography that uses digital technology to make digital images of subjects. Digital image capturing devices, such as digital cameras, include sensors that capture images in a digital form. Examples of such sensors include charge coupled devices (CCDs) and CMOS (complementary metal-oxide-semiconductor) sensors. Digital images can be displayed, printed, stored, manipulated, transmitted, and archived without chemical processing.
A problem in digital photography is that a user taking a picture may undesirably tilt the camera while taking the picture. As a result, the resulting captured image may be undesirably rotated within the image plane. Some computer applications enable the in-plane rotation (herein referred to as “tilt”) to be removed from a captured image by enabling the user to manually input a tilt angle (either numerically or with the help of the mouse pointer). The computer application rotates the captured image by the angle input by the user to remove the undesired tilt.
When textual documents are scanned, sometimes the scanner receives the documents in a tilted position. As a result, the scanned versions of text documents may include tilted text (i.e., oriented at an angle). Some applications enable tilt to be automatically removed from scanned text documents. This feature is typically referred to as “deskew,” and is available in some optical character recognition (OCR) applications, for example. However, such applications cannot perform deskew on natural images that include non-textual image features. For instance, such applications cannot perform deskew on digital images captured by digital image capturing devices.